As is well known to those skilled in the art, middle distillates such as diesel oils, cracking stocks, and catalytic cycle oils as produced are characterized by various deficiencies including poor cetane number and burning quality.
It is common to attempt to improve the quality of these hydrocarbon stocks by extracting the undesirable components which are responsible for the deficiencies. These stocks may for example be treated with N-methyl pyrrolidone which may extract aromatics, olefins, and compounds of nitrogen, oxygen, and sulfur from the middle distillate oil. The treated oil is typically characterized by improved properties.
A substantial portion of the cost of an N-methyl pyrrolidone treating unit lies in the several distillation columns and associated equipment including fired heaters, heat exchangers, pumps, etc; and the cost of operation is clearly large because of the cost of heat and power associated with these operations.
It is an object of this invention to provide a novel process for N-methyl pyrrolidone treating of middle distillates. It is a particular object of this invention to provide a process which minimizes the need to provide distillation steps and which permits substantial savings in operating costs. Other objects will be apparent to those skilled in the art.